Unsaturated carbonate ester and polymer thereof



Eatented July 2, 1946 UNSATURATED CARBONATE ESTER AND POLYMER THEREOFIrving E. Muskat, Ari-on,

Norton Center, Ohio,

Plate Glass Company,

.and Franklin Strain,

assignors to Pittsburgh Pittsburgh, Pa, a corporation of Pennsylvania NoDrawing. Application March 7; 1942,

Serial No. 433,832

. 8 Claims. Y 1

This invention relates to a new class of unsaturated esters havingvaluable uses as resin intermediates. The new compounds are diesters of(a) .a glycol containing at least three carbon atoms in a continuouschain and (b) a half ester. of carbonic acid and an unsaturated alcohol.

The new compounds are esters of unsaturated alcohols. Preferably, theyare esters of alcohols containing 3m 5 carbon atoms and which have anunsaturated linkage in an aliphatic chain such as allyl, 2-methallyl,2-chloroallyl, Z-ethylallyL.

crotyl, isocrotyl, chlorocrotyl, tiglyl, angelyl, isopropenyl, alcohols,methyl vinyl carbinol, propargyl alcohol, butadienyl alcohol, divinylcarbinol, etc. Although esters of the'short chain alcohols are preferredthose of alcohols-containing up to ten carbon atoms are also useful, forexample, esters of linalool, .cinnamyl alcohol, chlorocinnamyl alcohol,phenyl propargyl alcohol, diallyl carbinol, l-hydroxy hexadiene-2,4,propyl allyl alcohol, n-octenol, etc.

The new compounds are unsaturated dicarbonates of glycols containing acontinuous carbon chain of at least three carbon atoms. Suitable glycolsare propylene glycol, trimethylcne glycol, tetramethylene glycol,pentamethylene glycol, pinacone, dimethyl ethylene glycol, 1,3-dihydroxybutane, etc. The new compounds have the structure:

m-o-o-oan-o-c-o-R.

. in which R1 and R: are radicals derived from the unsaturated alcoholsand R2 is the radical derived from theglycol.

The new esters may be prepared by treating the above glycols withphosgene at temperatures between 0" C. and 20 C. by bubbling the gasthrough a reaction flask submerged in an ice bath or an ice-salt orother freezing mixture. The re sulting dichloroformate of the glycol isthen reacted with an unsaturated alcohol in the presence of pyridine orother tertiary cyclic amine or a carbonate, oxide, or hydroxide of analkaline or alkaline earth metal. The latter reaction is per formed byadding the chloroformate to a mixture of the alcohol and alkalinereagent. The reagents are combined slowly to permit the dissipation'ofthe. heat of reaction. The same new esters may alternatively be preparedby reacting the phosgene with the unsaturated alcohol to form thechloroformate and subsequently reacting the chloroformate with theglycol in the presence of an alkaline reagent.

. Both the chloroformate preparation and the zene, toluene,

esteriflcation are exothermic reactions and are Where, however, aslightly agent is used, the reaction temperatures, 50 to promote aneconomical rate of reaction. Although the reactants may be combined invarious proportions and by various methods, it is usually preferred toadd the chloroformate to a mixture soluble alkaline reis slower andhigher 0., may be required to of alcohol and an excess of alkalinereagents The reactions may be conducted in the presence of an inertsolvent such as chloroform, carbon tetrachloride, acetone, ether,benzene, or petroleum ether.

The new unsaturated carbonates are generally non-resinous compoundshaving distinct boiling and melting points and are often capable ofseparation in substantially pur state. Frequently, however, theimpurities are side reaction products which are colorless andtransparent esters having characteristics similar to the esters hereincontemplated. In some cases removal of the impurities maybe unnecessarwhere they do not produce any detrimental efiect in th use of the ester.The new compounds are usually liquids at room temperature but some,however, are solids. The new unsaturated compounds are usually misciblewith solvents such as benchloroform, diethyl ether, carbon tetrachlorideand petroleum ether. The monomeric esters are valuable as plasticizersfor various resin materials such as styrene, cellulose, vinyl, urea,protein, phenolic, or Other uses such as solvents, insecticides, andliquid coating compositions are noteworthy.

These esters may be polymerized in the presence of heat, light, orcatalysts such as oxygen, ozone, or organic peroxides such as lauroyl,benzoyl, and acetone peroxides, to yield solid or liquid compositions ofwidely difiering physical'proper fusible and/or insoluble form. Thecompletely polymerized polyunsaturated compound are, in general,substantially unaii'ected by acids, alkalies, water, and organicsolvents. Intermediate polymers derived from the polyunsaturated estershaving a wide range of properties may be secured by incompletepolymerization. The polymers acrylic resins.

3 thus obtained are transparent and colorless, although they may attimes have slightl yellow cast, especially when polymerized completely.Many of these new polymers are generally tougher and more resistant toshattering than are the unsaturated alcohol esters of polybasic acids.

Upon the initial polymerization of the poly-, unsaturated esters in asolution of the monomer in suitable solvents, an increase in theviscosity of the liquids is noticeable due to the formation of a simplepolymer which is soluble in the monomer and in sol-.- vents such asacetone, benzene, xylene, dioxane, toluene, or carbon tetrachloride.Upon further polymerization, the liquid sets up to form a soft gelcontaining a substantial portion of a polymer which is insoluble. in themonomer and orin liquid monomeric state or game solvents and containingas well, a substantial portion of a soluble material which may bemonomer and/or soluble fusible polymer. These gels are soft and bendreadily. However, they are fragile and crumble or tear under lowstresses. They may be further polymerized in the presence of catalyststo the final infusible insoluble state in which substantially all of thepolymer is substantially infusible and substantially insoluble inorganic solvents, acids, amLalkalies.

The monomers of the polyunsaturated esters may be cast polymerizeddirectly to the substantially insoluble, infusible state. This procedureis subject to certain inherent dii'ficulties due to'the strains whichare established durin olymerization of the result in fractures as thefinal hard form is attained. It has been discovered that thesediiliculties may be avoided by releasing the strains established in thegel before the fracturing can occur. This may be done by permitting thestrains to be relieved before the polymerization is complete, eitherperiodically or by conducting the polymerization under conditions whichpermit radual release of these strains. For example, the polymerizationmay be conducted in a simple mold until a soft firm gel has formed. Atthis point the polymer may be freed from the mold to which it adheresstrongly. When released, the polymer contracts substantially, therebyrelieving the polymerization strains. The gel may thereafter be shaped,if .desired, and polymerized to the final infusible state. Smooth,optically perfect sheets may be made by this method. Preferably, theinitial polymerization is conducted at a temperature sufficiently low toprevent the complete decomposition ofthe peroxide catalyst. Thistemperature is dependent upon the catalyst used. For benzoyl peroxide,temperatures of 65 to for acetone peroxide, temperatures of 140-150 C.may be used. a In accordance with one modification, the gel after it isfreed from the mold may be coated on both sides with monomer or thesyrupy polymer. The coated article is then polymerized between smoothheated plates to the. final insoluble state. 1

In order to inhibit formation of cracks during the initialpolymerization, it is frequently desirable to minimize thepolymerization on one side of the sheet. This is done by conducting thepolymerization with one side exposed to the air which inhibitspolymerization in the presence of aperoxide catalyst such as benzoylperoxide. Thus, a sheet is produced which is hard and smooth on one sidewhile being soft and tacky on the other. The sheet may then be finished80 C. are suitable, while gel and which frequently Cast polymers mayalso be prepared by a single step polymerization directly to theinsoluble infusible state. The monomer may bemixed with one to. fivepercent of benzoyl or other organic peroxide and heated at 50-60 C.until it becomes partly polymerized and thickened to an increasedviscosity of 100 to 1000 percent of the monomer viscosity. The thickenedmonomer may then be polymerized between glass, metal, or similar plateswhich are separated by compressible gaskets or retainers of Koroseal(plasticized polyvinylchloride) butadiene polymers, polyvinyl alcohol,Thiok 1 p yethylene sulfide). rubber, or similar materials arrangedabout the edge of such plates. The thickened monomer may be poured onone glass plate within the confines of the flexible retainer, laid about2 inches from the ed e of the plate. The second glass plate then may becarefully laid on top, taking care to avoid the trap ing of air bubblesunder the top plate. When the top plate is in position, both plates maybe held together by means of suitable clamps which are capable ofapplying pressure upon the plates and are placed directly over theflexible retainers. The entire assembly isthen placed in an oven andheated at to C. where the polymerization is continued. During thepolymerization the resin shrinks and tends to draw away from the glasssurfaces. To prevent fractures pressure is'maintained upon the plates todepress the flexible retainer and permit the Plates to remain in contactwith the polymerizing resin.

This pressure may be maintained by periodically tightening the clamps orby use of spring clamps which maintains a uniform pressure throughoutthe polymerization process.

By an alternative procedure for east polymerizing sheets, the molds maybe assembled before tainer, preferably at one comer of the mold.

The assembled mold is then placedin a vertical position with the opencorner uppermost. The

thickened monomer containing one to four percent residual peroxide isthen poured in slowly until the entire mold is filled. After standinuntil all of the entrapped air has separated, the mold is heateduniformly between 70 and lOO" 0.110 continue the polymerization.Pressure is maintained upon the plates to insure the contact of glassand resin during p lymerization by suitable means such as by tighteningthe clamps periodically or by maintaining a uniform pressureupon theplates throughout by means of spring clamps. When the resin has beencompletely polymerized, it is separated from the glass plates and ahard, transparent, colorless, and. a

durable resin sheet is obtained.

Other methods have been developedifor-polymerization of the compoundsherein contemplated while avoiding formation of cracks and fractures. Byone of these methods the polymerization may be suspended while themonotacky side with monomer or syrupy be used as a molding powder solvedin suitable solvent for generally contains at least methods. It may beprecipitated by the addition.

ofnonsolvents for the fusible polymer such as water, ethyl alcohol,methyl alcohol, or glycol, and alternatively, it may also be separatedfrom the monomer by distiilationin the presenceof an inhibitor forpolymerizatio and preferably at reduced pressures. The fusible polymeris thus obtained in stable solid form and as such may or may be redisusein liquid form. It is soluble in organic solvents which are normallycapableof dissolving methyl methacrylate polymer or similar vinyl typepolymer.

Preferably, the new polymers of polyunsaturated esters are produced byheating the monomer or a solution thereof in the presence of substantialquantities, for example, 2 to 5 percent of benzoyl peroxide until theviscosity of the solution has increased about 100 to 500 percent. Thismay require from one-half to two hours while heating at 65 to 85 C. inthe presence of benzoyl peroxide. The resulting viscous solution .ispoured into an equal volume of water, methyl or ethyl alcohols, glycolor other nonsolvent for the fusible polymer. A polymer usually in theform of a powder or a gummy precipitate is thus formed which may befiltered and dried. This permits substantially complete separation of asoluble fusible polymer from unpolymerized monomer.

Often, however, such complete separation is.

not desirable since hazyproducts may be secured upon furtherpolymerization. Accordingly,

materials such as pyrogaL- thegel is still fusible. tion .maybe-disintegrated to a pulverulent'form and used as a molding'powder.Alternatively, a desirable'polymer may be prepared byemulsifying themonomer or a syrup polymer in an aqueous medium with or without asuitable emulsiflcation agent such as; polyvinyl alcohols, polyallylalcohols, etc., and then polymerizing to the point where the'gelprecipitates. This polymer may be separated andused as molding r- Thesolid forms of the fusible polymers may be used as molding compositionstoform desir- I ate. lead. chromate, magnesium calcium silicate, andplasticizers,

it is often desirable to produce compositions com I prising the fusiblepolymer and the monomer. This may be effected'by partialdistillation orextraction of monomer from the polymer or by reblending a portion of thefusible. polymer with the same or a different polymerizable. monomer Ingeneral, the composition should contain at least 40 percent andpreferably in excess of'50 percent fusible polymer and from about 5percent to or percent monomer.

Preferably, the production of these materials is conducted by treatmentof a solution'of the monomer in a solvent for monomer and polymer suchas benzene, xylene, toluene, carbon tetrachloride, acetone, or othersolvent which normally dissolves vinyl polymers.

. Other polymerization methods may involve the interruption of thepolymerization while the polymer is a gel. For example, a soft solid gelcon-. taining a substantial. portion of fusible polymer may be digestedwith a quantity of solvent for the fusible polymer to extract thefusible gel from the infusible. Thesolution maythen be treated as abovedescribed toseparate the fusible polymer from the solvent. Thesepolymers may be used as molding or coating compositions. Due to theirsolubility, they are particularly desirable for use in paintcompositions.

Other fusible polymers may be prepared by carrying the initialpolymerization to the point where the polymer is in the, form of a gelwhich 20 percent and preferably about 45 to 80 percent by weight ofsubstantially insoluble polymer, but at which point a-ble moldedproducts which may be polymerized to l a thermohardened state.Preferably, the molding is conducted in a manner such that the polymerfuses or blends together to form .a substantially homogeneous productbefore the composition is polymerized to a substantially infusiblestate; This may be eifected by conducting polymerization at an elevatedtemperature and/or pressure in the presence of benaoyl peroxide,generally in a heated mold. The polymers may be mixed with fillers, suchas alpha cellulose, wood pulp, and other fibrous substances, mineralfillers or pigmentssuch as zinc oxide, calcium carboncarbonate and suchas the saturated alcohol esters of phthalic acid, camphor, the saturatedalcohol esters -ofmaieic, fumaric, -succinic,'and adipic acids or diortriethylene glycol: bis (butyl carbonate). The polymeric -molding powdermay be oopolymerized with -metal, cloth, wood, leather orsynthetictr'esins may be coated with the solution of polymer in solventand subsequently polymerized to yield attractively finished coatings.Similarly, porous objects of felt. cloth, leather, paper, etc., eitherin single layers or laminated, may be impregnated with the dissolvedfusible polymer and subjected tothe polymerization to the final in-.soluble infusible state. Other molding powders may be prepared from thenew esters without first converting. them to the intermediate polymer.The monomer may be mixed directly with'a suitable filler such asmagnesium carbonate, cellulose pulp, asbestos, etc., ina ball mill orother mixing device. j By proper selection of'proportions 2. dry pulerulent powder can be obtained which is capable ofpolymerization underthe influence of heat and pressure to a' glossy solid polymer of hightensile strength. The use of too much filler will cause a non-glossyfinish and the use of too much monomer will make the powder moist anddiiiicult to handle. Sometimes itmay be desirable'to pre'cure themolding powder by subjecting it to a moderate temperature of 50 to 70 C,for a limited period of time, for example, one to three hours. Thisprocuring operation is a partial polymerization and permits, a drymolding powder where the sameproportions of 6 This solid resin composi-8 moles (230 grams) of propylene glycol (1.2-

wminu 'item ester was dried over f lauroyl peroxide and heated hour.hard, colorless esin was produced.

1 ice bath in a- 2-liter chloroformate was added grams per minute. whenthe chloroiormate ad-.

"with,

one glycol bis can:

" Further details or the iesters and of their applications will be .1from the following examples.

Q trample I apparent 'idihydroxy propane) was placed in a flask pro-;vided with a submerged in'an ice bath. Phosgene was passed ;intothe-flask at the rate oi. 100 miilimoles per for 70 minutes. During thereaction the rature of the reaction vessel remained be- +l8 C; Thepropylene glycol washed with water and dried itween +5 and 1dichloroi'ormate was 350 grams of allyl alcohol grams of pyridine andThe dichiorothe continual mainte- When and then with sodium Example 11 Amixture of 160 grams of trimethylene glycol, (1,3-dihydroxy propane) and500 cc. of 50 per- +2 C. on an flask. With constant stircent NaOHsolution was cooled to ring the mixture-was added to 480 grams of allylchloroformate in 200 halt-hour, the addition was made 7 the end of anhour it was 10 grams per minute. The balance-oi the at the rate of -25dition was completed the mixture was stirred for perature remainedbetween 0 c. and 12 c. The benzene solution was washed with dilute HCland water and dried over CaClz. The trimethyl- (allyl carbonate) waspurified by distillation. The ester isa colorless high boiling liquid,believed to have the structure: 1

H: m CHFCH-CHr-G-C- A gram sample was mixed with 5 percent acetoneperoxide and heated at 135 C. for one hour. A hard, transparent, andnearly colorless solid polymer was produced.

stirring mechanism. The flaskwas- 1.44 14. Its structure was mixed with3 percent 1 cc. benzene.- For the flrsti at the rate of w 1 5v grams perminute. The rate of addition was slowly increased until at synthesis ofthese newi I Ef 'plem "Two moles-oi 2-chloroa1lyl alcohol use grams) wastreated with phosgene at 0-10? C. The chlollyl alcohol roduced wasroiormate oi 2-chloroa washed with dilute HCl dried over anhydroussodium sulphate and distilled at 2 mm. pressure.

. 175 grams pyridine, and

I One mole of tetramethylene glycol .(90 gram!) 1000 cc. of benzene weremixed in a two-liter flask equipped with a dropping tunnel and stirringdevice. The mixture was cooled to -2 'C. on a salt-ice freezing mix- I vture- The chloroiormate or chloroallyl alcohol over anhydrous NaaSOe Itwas distilled at} l 1 mm. totalpressure. Y 9 1 equipped with a stirrerand pro- A vided with mice bath was charged with 500 was added slowly atI chloride fate was formed hydroxy propane) was. then added at a ratelust slow eno sn to keep the reaction temperature below 12 C. Thereagents were completely combined in about. one

p I The benzene solution. containing the new ester was washed withdilute I-lCl and with water. The benzene was vaporized by heating at241mm. v ester was a liquid round to have the structure:

. cm=c-cm-o-c-o-crn V 1 I Y H! 01 c HI CHr-fl'J-flflr-O-JJ-O-CH: IExample lV Using the procedure or Example 11, except that methallylalcohol was used in place of allyl alcohol an ester believed to have thefollowing structure was synthesized:

' en. H;

. om o In cHFd-om-o-E-d Example V g Flitygrams or tetramethylene glycolbis (chloroallyl carbonate) was mixed with 3 percent benzoyl peroxideand 60 cc. benzol. The solution was heated at 60-65 which the liquidbecame quite viscous. The benzene solution was then poured ethylalcohol. A transparent flocculant precipiwhich aiter'settling wasdecanted, washed with water and dried. Ten grams of the polymer wasmixed with an additional 3 percent benzoyl peroxide and pressed in amold at 1500 pounds per. square inch at C. A slightly yellow transparentpolymer was produced.

Example VI A '15 gram sample of propylene glycol (1,2-diand 500 cc. ofbenzene were placed in a reaction flask equipped with a stirringmechanism and dropping tunnel. The flask was submerged in an ice bathand stirred until the temperature fell to +5 C. with constant stirringphosgene was bubbled in at a rate low enough to permit the temperatureto remain at or below 5 C. The bis(chloroformate) dissolved in benzenewas washed with water and dilute NarCOz solution and dried overanhydrous sodium sulphate. The chloroformate was then purifled bydistillation at 2 mm. total pressure.

A mixture of 200 grams pyridine, 300 cc. benzene, and grams of methallylalcohol was prepared and cooled to 0 C. in a reaction flask submerged inan ice bath. The bis(chlorolormate)' of propylene glycol was addedslowly at the rate or 3 grams per minute for 30 minutes and5 grams Thenew unsaturated.

C. for two hours during into 300 cc. of.

ester, which was separated from the benzol and other impurities bydistillation, was believed to have the molecular structure:

A mold was prepared by clamping two sheets of polished plate glass (12"x 12") with a strip of Koroseal (38f' x A" x /2") between. The flexibleKoroseal strip was placed about 1 to 1 /2" from the edge of the glassplates with the ends about 1 inch short of butting at one corner. Theplates were held together with C clamp placed directly over the flexibledivider. The mold was placed in a vertical position with the open corneruppermost.

About 500 cc. oi. 1,2-propylene glycol bis (methallyl carbonate) wasthickened by heating for two hours at 60 C. in the presence of 3 percentbenzoyl peroxide. The thickened ester was then poured into the moldslowly to avoid entrapping air bubbles. The mold was then heated for 20hours at 80 C. During the heating the C clamps were tightened every fourhours to recover the pressure lost by the shrinking of the resin. Themold was then taken apart and the product was a sheet of resin clear andalmost colorless with an optically perfect surface.

Example VIII About 200 cc. of trimethylene glycol bis (allyl carbonate)was mixed with 20 grams of cellulose pulp. .5 gram cadmium yellowpigment, and '3 percent acetone peroxide. The mixture was heated forfour hours in an atmosphere of CO: maintained by a stream of the CO:passing through the covered tray. The composition was pulverized andscreened. A sample was pressed in a 10 mold under 1800 pounds per squareinch at a temperature of C. The product was hard, glossy,semi-translucent, and of a uniform brilliant yellow color.

Although the invention is described with respect to certain specificexamples, it i not intended that the details described shall belimitation upon the scope of the invention except as expressly includedin the appended claims. This application is a continuation-impart ofSerial N05. 361,280, filed October 15, 1940, and 403,703,

filed July 23, 1941, Franklin Strain.

We claim:

1. 1,2-propylene glycol bis (allyl carbonate).

2. Trimethylene glycolv bis (methallyl carbonate).

3. Tetramethylene glycol bis (chlorallyl carbonate).

4. A polymer of the 1,2-propylene glycol bis (allyl carbonate).

5. A polymer of trimethylene glycol bi (methallyl carbonate) 6. Apolymer of tetramethylene glycol bis (chlorallyl carbonate) 7. Acompound corresponding to the following structural formula:

by Irving E. Muskat and claim 7.

IRVING E. MUSKAT. FRANKLJN STRAIN.

